This invention relates to an apparatus for relieving muscular tension at a workstation which requires use of one""s hands or feet. More particularly, it relates to an apparatus for use in conjunction with a computer or other keyboard to prevent the operator from having excessive upper body tension as well as in conjunction with other instruments where arm support during hand assembly or control panel use is found to be an aid.
Operators of business machines such as word processors, computers and typewriters often find muscular tension in the back, neck and arms because the arms must be elevated and suspended over the keyboard. Furthermore, often the operator will remain unconsciously tensed in the ready position even though he is not entering data. This is motivated by the wish to keep the fingers in constant reference to special keys on the keyboard. When this happens for a prolonged period of time, the discomfort of muscular strain can occur during work there for lasting afterwards. Furthermore, when there is muscular tension it is common for the operator to make errors. To alleviate this, a large number of work breaks are required in order to relieve the muscular tension.
Various devices have been developed for use in conjunction with a keyboard enabling the operator to rest his hands or arms while operating the keyboard. Some of such devices are disclosed in U.S. Pat. Nos. 4,482,063, 4,481,556, 4,482,064, 3,300,250, and 1,801,669. However, all of the devices disclosed in the above referenced U.S. Patents are static; therefore, there will be an amount of friction between the person""s arms and the contacting surface of the device when sufficient movement of the hands a across the keyboard in the horizontal plane is attempted. Such movement of the hands calls for a momentary lift of the arms from the surface to avoid friction which can suddenly release or bind depending on skin moisture, adhesion, and the texture of the surface.
A further problem arises in the use of cursor control devices which are either not on the keyboard or form part of a numeric keypad located adjacent to the keyboard. The cursor control device may be a speed aid but the hand(s) must be removed from favored reference keys on the keyboard to use such as control. Although it would be advantageous to have the cursor device in continuous contact with the operator all fingers are usually already committed to keyboard contact.
Consider a simple generics and repetitive task of picking up a delicate object with a forceps at one location and depositing it in a proper orientation at a new location. An arm rest to aid the, hand would be desirable at two locations the object, source, and find destination but even then the arm would have to transport between these supports and guard against too forceful an impact with the second site. Again static supports may create erratic effects of friction against the skin. Perhaps the second site of deposit might be also moving on a slow assembly line or the assembly process could be enhanced by such movement. Additionally other variations could entail more than one site source for acquiring special parts or multiple deposit site.
To address these assembly problems, two or more arm rests could be of benefit even disregarding the act of moving between sites. Rather than a multiplicity of static supports, a moving support would be beneficial, including a support which eliminates the requirement of multiple landing impacts.
Even disregarding direct hand assembly of small parts, the operation of such that arm fatigue occurs while remaining at one or more switch sites types of hand controls or switches on diverse panel arrangements may benefit from arm support especially if the switches require constant adjustment for various processes.
In these applications each has a distinct range of work surfaces or panel arrangements but they have a common need for aid to hand function by means of arm support. The arm support should cater to various demands on the operator including; ongoing use at a dominant location or control, non-use of the hand but maintaining a ready position at a favored location, and support during transfer and landing at new locations.
Generally a foot operates a control rather than directly manipulating an object such as in part assembly. In common practice the leg is supported by the heel and the control is affected by both ankle and foot motion. When more than one control is addressed or there is need to modify pressure on a single variable control then tension in the leg and the muscles of the abdomen and lower back may be required. Support at the lower leg would provide benefits analogous to arm support for hand functions. Because leg mass and muscle groups are primarily used for body transport the effort to elevate the weight of a leg for protracted tasks is perhaps more unusual and distracting to the effort of coordinating foot and ankle function than the act or reaching with the arm for hand functions. Sometimes foot controls may be useful in situations where the operator must be relatively supine, prone, or reclining on the side such that differing muscle groups must contend with a disadvantageous support of the extended leg. Since foot controls are often used on heavy machinery, issues of fatigue and accident prevention are at stake rather than the issue of keyboard error.
As discussed gravity can produce fatigue; and predictable motion, such as that of an assembly line, can create new functional demands. However, when the whole environment of the operation is affected by motion such as operation onboard any type of vehicle, then shifting relationships of the vehicle and a work surface, keyboard, or instrument panel can occur with respect to the operator who has an independent inertia. A seat belt merely constrains an operator""s main body to these changes. An outreached limb performing tasks also experiences inertial shifts and could benefit from a limb support which at least partially imparts motion that approximates the to the limb of the fixed work items which are unboard. To compensate for a sudden downward shifts, a seated operator in motion can maintain a constant downward pressure on a support and with training an unconscious compensation is in place to follow sudden down shifts of reduced G force. However, such constant downward reference would increase the friction against any static support and use against an arm or leg surface. Uplift, which represents increased G force, and some amount of side to side force can be imparted to an arm or a leg by way of the support which is fixed to the moving craft. If uplifts are constant to significant levels of G force, then fatigue may become a major obstacle to effective limb operations which can be compensated by supports. In vehicles with complex manual vehicle control systems, or complex procedures carried on for other than vehicle control, operator limb support may be desirable with the same concerns range and continuity of contact as previously described.
An inadequacy of strength in some muscle groups of a given limb in use may affect the accuracy and endurance of an otherwise achievable distal hand or foot function. This situation could be caused by birth defect, direct injury, neurologic events, and also a unique class of proximal muscular dystrophies. Again the issues of continuous proprioceptive contact with support over a range of locations are pertinent. Incorporation of a convenient data acquisition or control device, such as cursor movement, directly into the support may be of even more value to the handicapped operator.
Furthermore having a support which eliminates friction against fixed surfaces and which allows for continual support during movement between sites would be desirable.
A basic method of safety control of machines is to provide safe zones to which the hands or feet must be placed to activate the machine controls. These safe zones are another movement in the work process and the switches at the safe zones are another target of manipulation. In a process such as assembly that requires arm movement at a vulnerable location, it may be beneficial to have a moveable arm support both to move the support from the area of machine action along with the appendage and to guide the appendage to the safe zones and site of machine control.
There is also a need to provide zones of safety for users of potentially dangerous equipment which provides for machine activation without danger to the limbs.
It is therefore one object of this invention to provide an apparatus for relieving muscular tension for a machine operator or control panel operator who uses his arms or legs.
It is another object to provide an apparatus for enabling a keyboard operator to work more efficiently and effectively for longer periods of time.
It is another object to utilize an apparatus which provides constant support and proprioception and minimum friction with the support during movement between desired limb positions.
It is another object to provide an apparatus for supporting one""s arms or legs while providing information through a sensor.
It is still another object to enable a keyboard operator to provide information, especially continuously variable direction information to a computer or other machine control systems without using one""s thumb or fingers and allowing the operator to maintain the arms in continuing support during movement and also freeing the thumb or fingers from cursor duties, allowing their continual contact with the keyboard.
It is still another object to enable a supported limb to be assisted by a movable support between disparate zones of work and safe zones or sensing zones where engagement of machine control is exclusively desirable.
In accordance with one form of this invention, there is provided an apparatus for supporting one""s arms while one""s hands are used at a workstation. One application is that of a keyboard for data input or computer. control. The apparatus includes at least one roller adapted to contact a portion of the arm. An axle whether virtual or real is provided to support the roller and to permit the roller to rotate. Preferably the also axle defines a path of side to side positioning for the roller.
Although curved axles could be used in certain settings, the straight axle is normally adequate for most applications.
The axis of rotation could be offset from the axis of slide including rotation on a raceway suspended below the axle or carried upon a trolley apparatus which rides on the axle path, however in the chosen form the axis of rotation and of slide are one and the same, consisting of a real axle through the center of the roller.
Preferably two rollers are used so that each arm is supported. Although various cross sectional shapes of rollers could offer aid to forward and back motion of the forearm across the support axle, including a plain cylinder, the cross section preferred is a cylinder with a larger flared diameter at each end so that the arm will engage the cylinder to carry it in lateral movements along the axis of slide. Various materials can be turned to this shape in solid form, however the preferred cross section should be hollow for lighter weight and so that the spine roller can travel on curved axles which might be selected for various applications. This also reduces bearing surface area to only the two ends of the roller where a simple durable bushing is a enchancement.
The above described configuration is preferred although the roller and an axle could be a single unit which only rotates and only slides at bearings housed in support brackets to either side.
Although the preferred axle described could be permanently anchored to a work surface or desk which supports the keyboard, a clamping system may be provided to allow for removal. The clamp may employ a compression and an expansion screw similar to a carpenter""s clamp but additionally it may allow for movement along a bracket. Also since the exposed underside of a desk top overhang may be only part of an inch, there may be a provision for the lower jaw piece to have the smaller bite or larger bite in two choices of orientation.
Although the axle could be clamped in one position in relation to work surface, preferably the bracket is provided with the axle at desired distances out from the desk top. Another extension may also be provided to allow for adjustment of the axle up and down. The preferred objective is adjustability outward and downward from the front edge of the work surface while other adjustments could be provided by other orientation for other work settings. While the adjustments could be intermittent choices, continuously sliding adjustment with slots is possible, and preferred.
The keyboard in use could be contained entirely on the desk top, however additional pieces that brace the brackets may also safely support the keyboard partially off of the desk top and incline it somewhat.
While the preferred form addresses support for table top keyboard use, various platforms for under table or under shelf suspension can allow for attachment of both the roller axle apparatus support principle and keyboard support. Where the security and convenience of drawer enclosure of the keyboard is desired an axle attachment is also adaptable. Since the drawer provides for inward outward motion of the axle, and the keyboard position along the drawer bottom is selectable, the axle needs only to retract from the drawer to allow roller rotation and some adjustability up and down. In a form for drawer mounting-a slotted square tube mount is retained as a pivoting bracket selectable some vertical adjustment of axle height during use.
In the embodiment where data input is determined by roller motion, which also allows in relation to a single sensory location can generate amplitudes in four vectors. Two vectors are provided by counting rotation increments clockwise or counterclockwise. Two more are obtainable by proximity sensing in the slide range either closer to or further from the sensor. Since the rollers move in the duty of support a switch may function when roller motion is to be translated into data input rather than mere ergonomic support. If a separate key or footswitch is provided to enable the mode of roller data input, then all vectors of each roller and multiple sensors can be used to generate data. In the one form, only the rotational vectors of each roller are sensed for directional and continuously incremented data generation. The proximity sensing in the slide range is relegated to enabling the data input mode, which is either on or off rather than continuously incrementable.
Mechanical rotation can be converted to electrical data by either analog or digital devices and ultimately may be converted to digital form for computer use or analog form in machine controls.
Analog signals are commonly generated by variable resistors moved by rotation. Various integrated, circuits can retain prior resistance values for comparison to newly received values to determine amplitudes of rotation. Directions of rotation can also be determined by ratio comparisons of two circuits on a variable resistor.
Digital signals can be generated by mechanical counts of cogs or bumps on a surface, but in more current technology photodiode sensors and circuits are employed to count on/off signals of light/dark patterns. One sensor can count amplitude and a pair of sensors arranged out of phase can provide data to determine direction of rotation for a given roller.
For either mechanical or photosensing of rotation, the portion of the roller sensed may be either the cylindrical or truncated surface, which is preferred in this application. Sensors for each roller may also be separated in location or provided in a housing unified, which is preferred.
In the preferred forms both a friction wheel variable resistor sensor and a photosensor reading barcode are shown in a composite example. The sensor locations for each roller are unified centrally for conservation of wiring and material and because an operator using both hands on the keyboard nonetheless usually has a space between the arms. The data input mode is enabled by an intentional central sliding motion by the operator""s arms to engage either the friction wheel (analog example) or a contact switch (in The photosensor example) obviating the need for a footswitch or other switch for enabling the mode of roller data generations. However, a simple foot switch to enable the sensing mode may be provided for some applications.
Generating continuous incremental data from the slide range of the rollers can be conceived in at least two methods.
A source of analog data derived from a variable resistor can be obtained if the axle is modified to contain a longitudinal gradient of resistance and the moving roller can provide a variable contact. In such a design the altered axle could be various cross.-sectional shapes including one with a longitudinal groove to contain the resistance gradient, which is insulated from the axle. A contact pointer touching the exposed resistance gradient could conduct to the axle itself, effectively maintaining a complete circuit with a variable range of resistance positions which can be used to calculate direction and amplitude for cursor movement.
A second method for locating a roller along a range of slide would be echo location sensors reflecting sound off of the truncate face of a roller. This method is not depicted, because it requires no unique adaptation of the roller and axle components, but only the mounting of an appropriate echo sensing system at a reference location.
The circuitry used to process and convert electrical signals derived from the above described system is according to commonly known principles.